Liquid skin cleaners contain a variety of surface active agents which perform several functions. These compositions generally contain surfactants, lathering agent(s), thickening agents, humectants and foam stabilizers. A disinfecting skin cleaner also contains antiseptic agents in combination with many or all of the preceding agents. The most commonly used antiseptic agents in disinfecting soaps are povidine-iodine (Disadine), chlorhexidine (Hibiscrub) and hexachlorophene (Phisohex).
The principle differences between conventional disinfecting soap compositions and the disinfecting epidermal cleaner of the present invention are (1) none of the components of this invention acting alone contribute a practical antiseptic activity to the product of this patent, (2) the inceptive bactericidal agent generated during the chemistry of this application is the free radical of iodide (or by-products) which is a fundamentally different chemistry from that of the antiseptic agents previously used in skin cleaners, and (3) the antiseptic activity of the disinfecting epidermal cleaner of the present invention does not cause irritation to the epidermis nor is it organoleptically aversive. The formulation of an emollient non-irritating antiseptic epidermal cleaner is only possible if the active antiseptic agents do not cause discomfort and are able to be formulated in an organoleptically unobjectionable medium.
The disinfecting epidermal cleaner as described in this specification is formulated to work upon admixture in an aqueous medium. Preferably a defined volume of water is admixed with the disinfecting components such that the individual components are diluted by 50 to 1000% upon use. That is, the concentration of the disinfecting epidermal cleaner of this application is designed to be diluted in water prior to use.
The essential constituents in commercial skin cleaning compositions are an antiseptic agent and a surfactant; however the final composition should exhibit high foaming, good water solubility, adequate detergency and acceptable organoleptic characteristics. Formulation of skin cleaning compositions containing conventional antiseptic agents has been problematical due to incompatibilities resulting from (1) destruction of the activity of said antiseptic agents, (2) phase incompatibility of said antiseptic agents, (3) long-term stability of said antiseptic agents in highly detergent compositions, and (4) achieving acceptable organoleptic properties. This application discloses the use of a composition containing peroxidase, peroxide and iodide in a prescribed formulation suitable for use as an antiseptic agent to form a disinfecting epidermal cleaner which does not suffer from the above incompatibilities.
For the peroxidase based composition of the subject invention to provide antiseptic activity in an epidermal cleaner the following must be-achieved: (1) the maintenance of enzymatic activity, (2) the maintenance of substrate (peroxide and iodide) concentrations within a defined range, (3) the absence of molecules or reaction by-products which meaningfully compete with iodide or peroxide for the active site of the enzyme, (4) the diffusion of the nascent bacteridcidal iodide radical (or by-product) from the enzyme's active site to targeted organisms, and (5) the absence of vitiating interactions between the bactericidal iodide free radicals and other components in the environment. The possibility of creating an effectual disinfecting epidermal cleaner whose biocidal ingredients are comprised of peroxidase, peroxide and iodide, can only be accomplished if the five requirements listed above are met.
It is known from Kessler (U.S. Pat. Nos. 4,476,108, 4,588,586 and 4,473,550), Orndorff (U.S. Pat. No. 4,370,199) and Montgomery (U.S. Pat. No. 4,576,817) that a biocidal formulation comprised of peroxidase, peroxide and a source of iodide is useful for disinfection in an aqueous non-viscous solution. The source of iodide must be ccapable of forming iodide ions upon dissolution in water in order for the system to function as a disinfectant. For purposes of the present invention non-viscous means a viscosity of less than 2.5 centipoises. The disinfecting applications described in the above identified patents take place either in a totally aqueous environment or upon a meaningful dilution or dissolution (greater than 10 fold) of a formulation to form a substantially aqueous environment. None of the previous applications involve disinfecting environments which are viscous and/or contain high concentrations of surface active agents required for a useful disinfecting epidermal cleaner.
The present invention may be used to disinfect any epidermal surface on either a human or animal. In fact, the present invention is particularly suited to the treatment of bovine mastitis.
The viscosity of commercial liquid soap cleaners are often at least about 5 centipoises and are typically above 20 centipoises and sometimes greater than 100 centipoises. The viscosity inherent to liquid skin cleaning compositions will reduce the diffusion of molecules relative to that in a substantially aqueous environment. The short-lived lifetime of the free radical generated by the removal of an electron from iodide imposes a constraint upon any system which uses peroxidase, peroxide and iodide as its active antiseptic agent. The free radicals generated at the active site of peroxidase must have enough time to diffuse to their ultimate site of action in order for the system to be effective. The diffusion coefficient, which is proportional to the rate of motion of a molecule in a matrix, is inversely proportional to the viscosity of a matrix. Every 10 fold increase in viscosity reduces the distance traveled of the iodide free radical per unit time by a factor of ten. Accordingly, the viscosity inherent in the high concentrations of surface active agents, including unsaturated fatty-acids, would be expected to decrease or eliminate the disinfecting ability of this system.
One skilled in the art of mechanistic organic chemistry would anticipate that the organic surface active agents of this invention would form a hostile environment for free radicals. A known parallel exists in the reduction or elimination of phenol catalyzed peroxidase/luminol chemiluminescence which is effected by the inclusion of molecules which interact with free radicals. In fact, any peroxidase catalyzed chemical event which requires the free radicals released into the environment from peroxidase to react with other molecules in solution can be affected by including exogenous organic material in the environment.